186 THE JOURNAL OF BOTANY 



12. Diachsea Fries. Lime present in stalk and columella, rarely 



wanting; entirely absent from the purple capillitium and 

 iridescent sporangium-wall. 



A. Sporangia globose : 



a. Lime in stalk white. 



Spores with dark raised bands and tubercles 



D. splendens Peck 



Spores spinulose . D. bulbillosa List. (12, p. 165*). 

 Spores delicately reticulated 



D. subsessilis Peck (9, p. 213, & 12, p. 166*). 



b. Lime in stalk orange D. Thomasii Kex 



B. Sporangia cylindrical : 



Spores nearly smooth ; lime in stalk white 



D. elegans Fr. 



Spores delicately reticulated ; lime absent in the two re- 

 corded gatherings D. cylindrica Bilgram (2, p. 524). 



Spores warted; lime usually absent D. caespitosa List. 



(syn. Comatricha ccespitosa Sturgis).t 



Order II. — Didymiace^e. 



13. Didymium Schrader. Sporangia stalked or sessile ; lime- 



crystals either scattered on the membranous sporangium-wall, 

 or closely combined and forming a crust ; capillitium often 

 thickened at intervals with dark nodes. 



A. Superficial crystals closely combined to form a thin egg-shell- 



like crust : — 



Sporangia sessile, pulvinate ; capillitium threads scanty, broad 



at the base D. difforme Duby 



Capillitium profuse, slender throughout 



D. difforme var. comatum List. (14, p« 8). 



Sporangia sessile, flat ; capillitium rigid, dark, profuse, slender 



at the points of attachment . . D. dubium Rost. 



Sporangia turbinate, shortly stalked ; capillitium rigid, colour- 

 less D. Trochus List. (12, p. 184*). 



B. Superficial crystals scattered, or loosely combined : 



a. Plasmodiocarps ; capillitium associated with large olive- 



coloured vesicles ....... D. Serpula Fr. 



b. Sporangia usually stalked ; capillitium without vesicles ; 



spores more or less spinulose 



a. Sporangia disc-sbaped with dark stalks D. Clavus Rost. 

 /?. Sporangia subglobose or effused 



Stalk and columella dark brown ; stalk opaque and granular 



D. farinaceum Schrad. 



t Further experience inclines us to regard this form as a species of Diach&a 

 distinct from D. Thomasii. 



